X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSetColumn.pm;h=430e35b4efbfc91621dd2f9f8c83fbbfbdc6fbc1;hb=26283ee38f220f6c6bae720ea5a189c9c0f47f6f;hp=4d0587a74b6e61658607b6d120dfe9c6ad46c64d;hpb=01dc6781d8cbc3466dd7ed15eb26999b0a91759a;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index 4d0587a..430e35b 100644
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -1,7 +1,12 @@
 package DBIx::Class::ResultSetColumn;
+
 use strict;
 use warnings;
+
 use base 'DBIx::Class';
+
+use Carp::Clan qw/^DBIx::Class/;
+use DBIx::Class::Exception;
 use List::Util;
 
 =head1 NAME
@@ -61,7 +66,7 @@ sub new {
   my $select = defined $as_index ? $select_list->[$as_index] : $column;
 
   # {collapse} would mean a has_many join was injected, which in turn means
-  # we need to group IF WE CAN (only if the column in question is unique)
+  # we need to group *IF WE CAN* (only if the column in question is unique)
   if (!$new_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) {
 
     # scan for a constraint that would contain our column only - that'd be proof
@@ -76,9 +81,17 @@ sub new {
 
       if ($col eq $select or $fqcol eq $select) {
         $new_attrs->{group_by} = [ $select ];
+        delete $new_attrs->{distinct}; # it is ignored when group_by is present
         last;
       }
     }
+
+    if (!$new_attrs->{group_by}) {
+      carp (
+          "Attempting to retrieve non-unique column '$column' on a resultset containing "
+        . 'one-to-many joins will return duplicate results.'
+      );
+    }
   }
 
   my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class;
@@ -125,7 +138,10 @@ one value.
 
 sub next {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   my ($row) = $self->_resultset->cursor->next;
+
   return $row;
 }
 
@@ -149,6 +165,8 @@ than row objects.
 
 sub all {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   return map { $_->[0] } $self->_resultset->cursor->all;
 }
 
@@ -172,7 +190,7 @@ Much like L<DBIx::Class::ResultSet/reset>.
 sub reset {
   my $self = shift;
   $self->_resultset->cursor->reset;
-  return undef;
+  return $self;
 }
 
 =head2 first
@@ -194,8 +212,38 @@ Much like L<DBIx::Class::ResultSet/first> but just returning the one value.
 
 sub first {
   my $self = shift;
-  $self->_resultset->reset();
+
+  # using cursor so we don't inflate anything
+  $self->_resultset->cursor->reset;
   my ($row) = $self->_resultset->cursor->next;
+
+  return $row;
+}
+
+=head2 single
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $value
+
+=back
+
+Much like L<DBIx::Class::ResultSet/single> fetches one and only one column
+value using the cursor directly. If additional rows are present a warning
+is issued before discarding the cursor.
+
+=cut
+
+sub single {
+  my $self = shift;
+
+  my $attrs = $self->_resultset->_resolved_attrs;
+  my ($row) = $self->_resultset->result_source->storage->select_single(
+    $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs
+  );
+
   return $row;
 }
 
@@ -379,10 +427,12 @@ See L<DBIx::Class::Schema/throw_exception> for details.
 
 sub throw_exception {
   my $self=shift;
+
   if (ref $self && $self->{_parent_resultset}) {
-    $self->{_parent_resultset}->throw_exception(@_)
-  } else {
-    croak(@_);
+    $self->{_parent_resultset}->throw_exception(@_);
+  }
+  else {
+    DBIx::Class::Exception->throw(@_);
   }
 }
 
@@ -396,7 +446,7 @@ sub throw_exception {
 #
 # Returns the underlying resultset. Creates it from the parent resultset if
 # necessary.
-# 
+#
 sub _resultset {
   my $self = shift;